flaps

Flap is a movable surface on a structure, attached along one edge, designed to extend, rotate, or reposition to alter performance or coverage. The term has specialized senses in aviation, medicine, and engineering. In each context, a flap changes local geometry or flow by adding or reorienting tissue or material.

In aviation, wing flaps are high-lift devices on the trailing edge. They increase the wing’s camber and, in many designs, the effective wing area, allowing higher lift at lower speeds. This enables shorter takeoffs and landings and steeper approach angles. Types include plain, slotted, Fowler, and combinations. Some aircraft also use leading-edge devices (such as slats) or other high-lift devices as part of a coordinated system. Flaps typically retract during cruise to reduce drag and are actuated hydraulically or electronically and synchronized with the flight control system. Flap scheduling affects stall behavior and landing performance.

In medicine, a flap is a piece of tissue moved to cover a defect while preserving a blood supply. Flaps are classified as local or regional (harvested from nearby areas) and free (completely detached and reattached elsewhere using microsurgery). They include skin, muscle, or myocutaneous varieties. Flap viability depends on vascular supply; risks include necrosis, infection, and donor-site morbidity. Flap reconstructions are used after trauma, cancer resection, or burns.

Beyond these domains, flaps can refer to any hinged or extendable panel designed to alter airflow or coverage in mechanical systems, packaging, or architecture, with the common feature of a pivot point along one edge.